Art of producing lip-type bags



March 19, 1957 c. K. BILLEB 2,785,609

ART OF PRODUCING LIP-TYPE BAGS Filed Jul :s, 1953 2 3 I'll v INVENTOR. [WT 4 United States Patent ART OF PRODUCING LIP-TYPE BAGS Clyde K. Billeb, Shorewood, Wis., assignor to Milprint,

c., Milwaukee, Wis., a corporation of Delaware Application July 3, 1953, Serial No. 366,013

7 Claims. (Cl. 93-18) The present invention relates generally to improvements in the art of producing bags, and relates more particularly to an improved method of commercially producing lip-type commodity bags from an advancing web of relatively thin and flexible sheet material and to an improved apparatus for performing the method.

A primary object of the invention is to provide an improved method of continuously producing commodity bags in a most expeditious manner with the aid of relatively simple and highly efficient automatically operable apparatus.

In the packaging industry, it is common practice to fabricate bags of lip construction from plastic films or sheet materials such as regenerated cellulose and the like; and such bags, generally referred to as lip-type bags, are formed with a protruding or male lip between the side edges at one end which is folded back upon a side wall and adhesively secured thereto to form the bag bottom and with a recessed or female lip between the side edges at. the opposite end of the bag to permit ready opening for filling purposes by means of automatic bag-filling machines. In the commercial production of these lip-type bags considerable difficulty is encountered in forming the lips at the opposite ends during the successive cutting operations; and only two commercially acceptable principles are presently in common use, the apparatus for exploiting these two principles being generally accepted by the industry as the only commercially practical types of equipment available. One of the two presently commercially available types of machines embodies the use of a former adapted to form the advancing web into a continuous tube, the tube former having a spring loaded reciprocating shoe located Within the formed tube and slidable therewith between the opposed cutoff knives during each cutoff operation so as to permit a straight cut to be made across one side of the tube by one of the knives and a lip-shaped cut to be made across the other side of the tube by the other knife, each of the knives thus cutting against opposite sides of the former shoe. However, while this reciprocating shoe type of apparatus has enjoyed considerable commercial success, the ultimate speeds of operation are undesirably lim ited to 16,000 to 18,000 cuts per hour by reason of the sliding shoe or anvil; and the friction of the sliding shoe Within the advancing tube has furthermore proven troublesome with unclean cuts often resulting. The other presently available type of machine for producing lip-type bags embodies the use of cutting knives acting against opposite sides of the advancing tube and pre-set with extreme accuracy to cut through a predetermined thickness of sheet material without need for a shoe or anvil as a backing or cushion for the knife edges, one of the knives performing a straight cut and the other knife cutting to form the lip. While this method and apparatus permits much higher speeds of production due to the elimination of the reciprocating shoe,

the application of the apparatus is undesirably limited and lacks flexibility in efliciently effecting changes for Patented Mar. 19, 1957 bags of different widths; and in addition, the accuracy with which the knives must necessarily be set necessitates the use of sensitive mechanisms which require careful care, inspection and adjustment to insure effective and accurate production. Although other attempts have heretofore been made to produce lip-type bags by somewhat different methods and with the aid of other types of machines, such attempts have all been generally conceded to be failures and not commercially satisfactory or acceptable for various reasons.

It is therefore a more specific object of the present invention to provide an improved method of producing lip-type bags and an improved apparatus for automatically and efiiciently performing the steps of such method which obviate all of the difiiculties and objections attendant previously proposed and existent methods and devices intended for like purposes.

Another specific object of my invention is to provide an improved method of and apparatus for commercially producing lip-type commodity bags in a most automatic and continuous manner and with utmost rapidity and efficiency.

Another specific object of this invention is to provide an improved simple and effective method of continuously converting a web of flexible and relatively fragile sheet material into successive lip-type commodity bags at minimum cost and with the aid of simple apparatus.

Still another specific object of the invention is to provide an improved lip-type bag-making unit which comprises relatively few parts, all of which are readily accessible for inspection, replacement or repair, and which is readily operable by a novice for exploiting the steps of the improved method with minimum care and attention.

An additional specific object of my present invention is to provide an improved method of producing lip-type bags, which comprises, longitudinally advancing a web of thin flexible sheet material, folding the advancing web along laterally spaced longitudinal lines with the longitudinal side edges of the web in overlapping relation to thereby form a continuous flat tube, firmly creasing the laterally spaced longitudinal fold lines of the tube, thereafter reopening the advancing creased web to substantially fiat condition, applying a longitudinal strip of adhesive to an edge portion of the reopened web, subsequently severing the advancing reopened and longitudinally creased Web transversely thereacross at spaced intervals and along lines extending substantially perpendicular to the longitudinal web edges between said edges and the fold line creases and offset therefrom between the spaced fold line creases to thereby provide successive sections, then refolding the successive severed sections along the creased fold lines with the adhesive strip positioned between overlapped side edges thereof to provide successive tube sections having a longitudinal side seam and complementary end lips, and finally folding an end portion of each tube section back upon itself along a transverse fold line and adhesively uniting adjacent surfaces thereof to form successive bags.

A further specific object of the present invention is to provide an improved novel apparatus for most efliciently exploiting the method and performing the several steps thereof as herein set forth.

These and other specific objects and advantages of the invention will be apparent from the following detailed description.

A clear conception of the several features constituting my present improvement, and of the steps of the improved method and details of the apparatus for performing such steps, may be had by referring to the drawing accompanying and forming a part of this specification, wherein like reference characters designate the same or similar parts in the several views. I

3 Fig. 1 is a moreor-less diagrammatic side view of a typical apparatus embodying the invention and adapted to perform the several steps of the improved bag making method in the production of side gusseted bags;

Fig. 2 is a similar diagrammatic top view illustrating the production steps of the method, portions of the apparatus having been omitted for the sake of clarity;

Fig. 3 is a transverse section through the advancing web taken along the irregular line 33 of Fig. l but with the creasing rollers as well as the parts of the reopening or secondary formers being separated from each other for the sake of clarity in illustration;

Fig. 4 is a somewhat enlarged fragmentary top view of the trailing portion of a severed section of the creased web immediately prior to the refolding thereof into tubular formation;

Fig. 5 is a similarly enlarged end view of the severed web section shown in Fig. 4; and

Fig. 6 is an enlarged fragmentary top view of the final refolding portion of the apparatus.

While the improvements have been shown and described herein as being particularly applicable in the production of so-called lip-type bags having side-gussets V and formed of regenerated cellulose or the like, it is not desired or intended to thereby unnecessarily limit the scope or utility of the invention, since the improvements may obviously be likewise advantageously utilized in the production of so-called square or flat ungusseted bags formed of any suitable flexible packaging materials; and it is also contemplated that certain specific descriptive terms used herein shall be given the broadest possible interpretation consistent with the disclosure.

In accordance with my improved method of producing lip-type bags, a web of thin flexible sheet material suitable for packaging purposes is continuously longitudinally advanced along apredetermined path. As the Web is advanced, it is folded along laterally spaced longitudinal lines with the longitudinal side edges thereof in overlapping relation to thereby form a continuous flat tube. Thereafter, the laterally spaced longitudinal fold lines of the tube are firmly creased in any suitable man ner. The advancing creased web is then reopened to 'substantilly flat condition as the tube continues to advance along a longitudinal but an abruptly inclined path. As the reopened creased web continues its advancement, a longitudinal strip of suitable adhesive is applied to an edge portion thereof, the adhesive strip being preferably interrupted at spaced intervals along the edge of the web. Subsequently the advancing reopened and longitudinally creased web is severed transversely entirely thereacross at intervals within the spaces between the successive longitudinal adhesive strips and along lines extending in a common plane substantially perpendicular to the longitudinal web edges between the web edges and the fold line creases but along offset lines between the spaced fold line creases to thereby provide successive sections. The successive severed sections are then refolded upwardly and inwardly along the creased fold lines with the adhesive strip of each section positioned between overlapped longitudinal edges thereof to provide successive tube sections having a longitudinal side seam and complementary male and female end lip portions, the refolding operation being accomplished during application of suction to the lower side of the web within the refolding zone and While the successive sections of the web continue their advancement. Finally, the male end portion of each tube section is folded back upon itself along a transverse fold line and the adjacent surfaces thereof are adhesively united to form the bottoms of the succe'sive bags. The method thus described results in the production of so-called flat bags, but the same steps may be followed in producing lip-type gusseted bags by the improved method. However, in the production of gussettedbags, thea'dvancingwebis initially foldedalong two laterally spaced series of longitudinal lines to thereby form a continuous flat tube having opposed gussets. Thereafter, all of the laterally spaced longitudinal fold lines of the tube are firmly creased, with the advancing creased web being subsequently reopened along the inermost fold line only of each series of fold lines to thereby return the web to substantially flat but only partially reopened condition, the partial reopening of the tube being preferably accomplished while the web continues its advancement along a longitudinal but abruptly downwardly and forwardly inclined path, Successive s laced longitudinal strips of adhesive are then likewise applied to an edge portion of the partially reopened advancing web, and the advancing partially reopened and longitudinally creased web is subsequently transversely severed at spaced intervals along lines extending between the longitudinal adhesive strips and substantially perpendicular to the longitudinal web edges between the edges and the innermost fold line creases of each series such creases but offset from such line between the innermost fold line creases of each series to thereby provide successive sections. The successive severed sections are then refolded along the innermost creased fold lines of each series with the adhesive strip of each section positioned between overlapped longitudinal edges of the web to thereby provide successive gusseted tube sections having longitudinal seams and complementary male and female end lip portions, the folding operation again being performed in the presence of suction on the lower side of the successive sections in opposition to the refolding operation and within the refolding Zone. Themale end portion of each gusseted tube section is then likewise folded back upon itself along a transverse fold line and is adhesively united to a side wall to form the successive gusseted bags.

in the commercial exploitation of the improved bag making method hereinabove described, an apparatus substantially as diagrammatically shown in the accompanying drawing may be effectively utilized, the apparatus shown therein being especially adapted for the production of lip-type gusseted bags but being readily adaptable for production of plain flat bags with equal effectiveness. Referring now to the drawing, the web 10 of relatively thin flexible sheet material is initially continuously longitudinally supplied from a rotatably supported supply roll 11, the web it) being advanced over a guide roller 12 past a former 13 adapted to fold the advancing web along laterally spaced longitudinal lines with the longitudinal side edges of the web in overlapping relation to form a continuous flat tube devoid of adhesive and with the folded tube edge portions indented to form gussets 15. The tube thus formed is then firmly creased by suitable means such as a pair of creasing rollers 14 which may likewise serve as draw rolls for withdrawing the web it) from the roll 11 over the guide roll 12 and tube former 13. The creased tube is thereafter partially reopened by means of a downwardly and forwardly inclined forming plate 16 adapted to reopen the advancing creased web it along the adjacent innermost fold lines only of the gussets 15, the web thus being partially reopened along the innermost gusset creases to substantially flat condition as illustrated in Figs. 3 and 5. As the partially reopened web it) leaves the reopening member 16, a longitudinal strip 21 of suitable adhesive is applied to an edge portion thereof by means of an adhesive applicator or glue applying wheel 17, the Wheel 17 preferably having an interrupted surface as shown at 1'7 in Fig. 1 so as to apply the longitudinal adhesive strips 21 in spaced series. To insure proper continued longitudinal advancement of the web 19 and to prepare the same for the final refolding operation, the partially rcopened web is drawn fromthe glue applicating Wheel 17 downwardly over the creasing edge of a second creasing member 18 about a guide roller 19 from which the web is advanced by means of cooperating draw rollers 20 to a cutoff device comprising cylinders 22, 23. As

the partially reopened substantially flat web is advanced between the adjacent peripheral surfaces of cylinders 22, 23, a cutoff knife 37 carried by the cylinder 22 severs the web transversely thereacross at spaced intervals between the successive longitudinal adhesive strips 21 and along lines extending substantially perpendicular to the longitudinal side web edges between such edges and the inner fold line creases of the web gussets and offset therefrom between the innermost gusset creases to thereby provide successive sections 24. Each of the successive sections 24 is then guided from the cutoff cylinders 22, 23 to a final tube former 25 by means of an endless belt 26, the final former 25 serving to refold the successive severed sections 24 along the precreased longitudinal fold lines with the adhesive strip 21 of each section being positioned between overlapped edges of the web 10 to thereby provide successive tube sections, each of which has a longitudinal side seam 33 and complementary male and female end lip portions 27, 28 respectively. Each tube section 24 is thereafter advanced from the endless belt 26 to a pair of cooperating tucker rolls or cylinders 29, 30, the tucker cylinder 29 having the customary tucker fingers 31 cooperating with the clamping recesses 31 of the clamping cylinder to thereby fold the male portion 27 of each of the successive tube sections 24 back upon itself along a transverse fold line and adhes-ively unite the adjacent surfaces thereof to thus finally form successive commodity bags 24 which are then fed to a conventional stacker 32.

The initial tube former 13 may be of more-or-less conventional design adapted to fold side portions of the web 10 upwardly and inwardly while indenting the same adjacent to the fold line to thereby provide side gussets 15. The adhesive applicator may also be of conventional construction with the glue applying wheel 17 receiving the adhesive from the periphery of a glue transfer and smoothing wheel or roller 34 which peripherally contacts a glue roll 35 operating partially submerged in a glue pot 36; and the tucker cylinder likewise operates in a similar conventional manner with the tucking element 31 thereof receiving glue from a transfer roller 37 operating partially submerged in a glue containing pot 38. The endless belt 26 may be driven in any suitable known manner about driving and guide rolls 39, and this belt 26 is preferably perforated as at 40 throughout its area to permit creation of a suction below the belt 26 in opposition to the former 25, the suction being conveniently created by means of a suction box 41 communicating with the inlet of a blower or fan 42 through a conduit 43, the blower being driven in a well known manner by a suitable motor 44. The various rolls and rollers may all be suitably supported in a well known manner on a supporting frame with the various drive and draw rollers being driven in an obvious manner; and to prevent smearing or spreading of the adhesive strip 21, the guide roller 19 may be provided with a peripheral groove or recess 45 as shown in Fig. 2. The inclined plate 16 for partially reopening the tube along the innermost gusset creases may be formed with a main body portion of a width equal to that portion of the web 10 falling between the innermost creases, and the trailing end of the reopening member 16 may be of somewhat larger transverse cross section as indicated at 46 so as to spread the folded tube flaps outwardly to partially reopened and substantially flat condition as shown in Figs. 3 and 5,

such partial reopening being effected along the innermost gusset creases of the tube.

From the foregoing detailed description, it is believed apparent that the present invention provides an improved method of an apparatus for economically and efficiently producing lip-type commodity bags in an extremely rapid and continuous manner. The apparatus for performing the improved method is simple,,highly eflicient and fully automatic as well as flexible in its adaptations in producing commodity bags of diverse sheet materials and forming lips of various widths and desired shapes. Since the successive sections 24 are cut from the advancing web 10 by a knife which is adapted to sever the web in partially open and flat condition instead of in tubular form, the knives 37 may be conveniently and quickly interchanged dependent upon'the width of the material or web 10 to be processed or converted, and the improved method and apparatus entirely eliminates the need for a reciprocating shoe or the like as well as the necessity for careful, accurate adjustment in the depth of cut. While the invention has been particularly described with respect to the production of lip-type gusseted bags, it may be used with equal success and efficiency in the production of plain flat ungusseted bags through use of the same apparatus performing the same steps as herein described. As indicated, the former 13 may be of conventional construction and design and the glue applicator 17 and glue transfer devices as well as the tucker and clamping cylinders 29, 30 respectively may likewise be of well known construction. The improved method and apparatus has proven extremely efficient and rapid in the commercial production of lip-type commodity bags, and it is of particular importance to first fully form the tube from the web 10 and to firmly crease the folds of the tube before partially reopening and subsequently severing the same into successive sections. It is likewise important in the production of these bags to perform the final refolding step in the presence of suction acting in a direction opposite to the folding mechanism, and the desired suction may be readily created by means of the suction box 41 and blower assemblage 42 as hereinabove described.

It should be understood that it is not desired or intended to limit this invention to the exact steps of the method or to the precise details of the apparatus herein shown and described since various modifications within the scope of the appended claims may occur to persons skilled in the art to which this invention pertains.

I claim:

1. The method of producing lip-type lbags, which comprises, longitudinally advancing a web of thin flexible sheet material, folding side portions of the advancing web upwardly and inwardly along laterally spaced longitudinal lines with the longitudinal edges of the web in overlapping relation to thereby form a continuous flat tube, firmly creasing the laterally spaced longitudinal fold lines of the tube, thereafter reopening the advancing creased web to substantially flat condition, applying a longitudinal strip of adhesive to an edge portion of the reopened advancing web, subsequently severing the advancing reopened and longitudinally creased Web transversely thereacross at spaced intervals and along lines extending substantially perpendicular to the longitudinal web edges between said edges and the fold line creases and offset therefrom between the spaced fold line creases to thereby provide successive sections, then refolding the side portions of the successive severed sections upwardly and inwardly along the creased fold lines with the adhesive strip positioned between overlapped side edges while applying suction to the lower side of the web in opposition to the direction of folding thereof to thereby provide successive tube sections having a longitudinal side seam and complementary male and female end lip portions, and finally folding the male end portion of each tube section back upon itself along a transverse fold line and adhesively uniting adjacent surfaces thereof to form succe ssive bags.

2. Apparatus for producing lip-type bags comprising,

means for longitudinally advancing a web of thin flexible dinal strip of adhesive to an edge portion of the reopened advancing web,'a knife'for severing the advancing reopened and longitudinally creased web transversely thereacro'ss" at spaced 'interva'ls 'and along lines extending substantially p'eripendicular to the longitudinal web edges between said edges and the foldli'ne creases and offset therefrombetweenthe spaced fold line creases to thereby provide successive sections, a final forming member for refolding the successive severed sections upwardly and inwardly along the creased fold lines with the adhesive strip positioned between overlapped side edges thereof to provide successive tube s ections' having a longitudinal side seam and complementary male and-female end lip portions, means for'c'reating asu'ction below the successive severed sections within the refolding zone, and means for finally folding an end portion of each tube section back upon itself along a transverse fold line and adhesively uniting a'dj'acent's'urfac'es thereof to form successive bags.

3. Apparatus for producing lip-type bags comprising, means forcontinuously longitudinally advancing a web of thin flexible sheet material, forming means for folding the advancing web along laterally spaced longitudinal lines with'the longitudinal side edges of the web in overlapping relation to thereby form a continuous flat tube, means for firmly creasing'the laterally spaced longitudinal fold lines of the advancing tube, means for reopening the advancing creased web to substantially flat condition, an adhesive applicator for applying a longitudinal strip'of adhesive to an edge portion of the reopened advancing web, a knife for severingthe advancing reopened and longitudinally creased web transversely thereacross at spaced intervals and along lines extending substantially perpendicular to-the longitudinal web edges between said edges and the fold'lines creases and offset therefrom bet'weenthe'spaced fold line creases to thereby provide successive sections, a perforated endless belt for thereafter receiving and conveying'the successive sections, a final forming member positioned immediately above said belt for refolding the successive severed sections along the creased fold lines with the adhesive strip positioned betweenoverlapped side edges thereof to provide successivetube sectionshaving a longitudinal side seam and complementary male and female end lip portions, means for creating a suction through the perforations of said belt within the refolding zone, and means for finally folding an end portion of each tube section back upon itself along a transverse fold line and adhesively uniting adjacent surfaces thereof to form successive bags. I

4. The method of producing lip type'bags, which comprises, longitudinally advancing a web of thin flexible sheet material, folding and creasing side portions of the advancing web along laterally spaced longitudinal lines with the longitudinal edges of the web in overlapping relation to thereby form a continuous flat tube, thereafter re-opening the advancing creased web to substantially fiat condition, applying-alongitudinal strip of adhesive to an edge portion of the re-opened advancing web, subsequently severing the advancing re-opened and longitudinally creased web transversely thereacross at spaced intervals to thereby provide successive sections, then refolding the side portions of the successive severed sections alongthe creasedfold line s-w ith the adhesive strip positioned between overlapped side edges while applying suction to one side of the web in opposition to the direction of folding thereof to thereby provide successive tube sections having a longitudinal side seam, and finally folding one end of each tube section back upon itself along a transverse fold line and adhesively uniting adjacent surfaces thereof to forrn'siicces sive bags.

5. Apparatus'for producing lip-type bags comprising,

means for longitudinally advancing a web of thin flexible sheet material, forming means for folding and creasing the advancing web along laterally spaced longitudinal lines with the longitudinal side edges of the web in overlapping relation to thereby form a continuous flat tube, means for re-opening the advancing web to substantially flat condition and for applying a longitudinal strip of adhesive to anedge portion of the rc-opened advancing web, means for severing the advancing re-opened web transversely thereacross at spaced intervals to thereby provide successive sections, a final forming member for folding the successive severed sections along the initial fold lines with the adhesive strip positioned between overlapped side edges thereof to provide successive tube sections having a longitudinal side seam, and means for creating a suction below the successive severed sections within the re-folding zone.

6. The method of producing lip-type bags, which comprises, longitudinally advancing a web of thin flexible sheet material, folding and creasing side'portions of the advancing web along laterally spaced longitudinal lines with the longitudinal edges of the web in overlapping relation to thereby form a continuous flat tube, thereafter re-opening the advancing creased web to substantially flat condition, applying a longitudinal strip of adhesive to an edge portion of the re-open ed advancing web, subs'equently severing the advancing re-opened and longitudinally creased web transversely thereacross at spaced intervals to thereby provide successive section's, thenrefolding the side portions of the successive severed sections along the creased fold lines with the adhesive strip positioned between overlapped side edges while applying suction to one side of the Web in opposition to the direction of folding thereof to thereby provide successive tube sections having a longitudinal side seam, and finally sealing one end of each tube section transversely thereacross to form successive bags.

7. Apparatus for producing lip-typebags comprising, means for longitudinally advancing a web of thin flexible sheet material, forming means for folding 'and creasing the advancing web along laterally spaced longitudinal lines with the longitudinal side edges of the web in overlapping relation to thereby form a continuous flat tube,

cans for re-opening the advancing web to substantially fiat condition and for applying a longitudinal strip of adhesive to an edge portion of the re-opened advancing web, means for severing the advancing re-opencd web transversely thereacross at spaced intervals to thereby provide successive sections, a final forming member for folding the successive severed sections along the initial fold lines with the adhesive strip positioned between over- I lapped side edges thereof to provide successive tube sections having a longitudinal side seam, means for creating a suction below the successive severed sections within the re-folding zone, and means for transversely folding an end portion of each tube section back upon itself and adhesively uniting adjacent surfaces thereof to form successive bags. 

